Device for sewing machines for cutting the edging of sewed materials

ABSTRACT

The disclosure relates to an improved cutting device for a sewing machine, the cutting device being of the type which is oscillated to cut a strip of material adjacent the seam as the material is being sewed to another material. Manually operated means is provided for rotating the cutting means against the feed direction of the materials being sewed so that the excess material can be separated when a sewing operation is complete. The device is constructed so that oscillation of the cutting device continues during the latter operation, called discharge cutting.

Unite States atent Wenz et al.

Sept. 4, 1973 DEVICE FOR SEWING MACHINES FOR CUTTING THE EDGING OF SEWEDMATERIALS Inventors: Herbert Wenz; Fritz Schwarztrauber, both ofKaiserslautern, Germany Pfaff Industriemaschinen GmbH,Kaiserslautern/Pfalz, Germany Filed: Nov. 1, 1971 Appl. No.: 194,649

Assignee:

Foreign Application Priority Data Nov. 5, 1970 Germany G 70 40 909.5

US. Cl. 112/127, 112/129 Int. Cl D051: 37/02 Field of Search 112/130,122, 123,

[56] References Cited UNITED STATES PATENTS 2,925,794 2/1960 Mayeran112/122 Primary Examiner-11. Hampton Hunter Attorney-0rville N. Greeneand Frank Lowell Durr [57] ABSTRACT The disclosure relates to animproved cutting device for a sewing machine, the cutting device beingof the type which is oscillated to cut a strip of material adjacent theseam as the material is being sewed to another material. Manuallyoperated means is provided for rotating the cutting means against thefeed direction of the materials being sewed so that the excess materialcan be separated when a sewing operation is complete. The device isconstructed so that oscillation of the cutting device continues duringthe latter operation, called discharge cutting.

2 Claims, 3 Drawing; Figures g 4 i i 5 PATENTED SEP 4197.! 3 74 am: 1 0F2 4 f X8 Fig.7 13 12 The invention concerns a mechanism for a sewingmachine for cutting the edges of sewed material in which the blade ofthe cutter is oscillated by means of an oscillating lever, drivenindependently of the movement of the sewing mechanism and which can beshiftedfrom its normal operating position against the feed direction ofthe material to be sewed to completely cut off the excess material.

For the cutting of lining materials such as shoe stock, cutting devicesare known which are equipped with an oscillating driven knife with aknife edge in a vertical plane and a horizontal protective flange abovethe blade angled away from the blade. A lining is thus cut close to thestitch line. There, the lining frequently projects also opposite to thefeed direction of the goods to be sewed somewhat beyond the uppermaterial, whereupon in the case where the seam ends at the edge of theupper material, the lining is cut only up to this edge of said uppermaterial.

In order that this overhanging or extending lining strip does not haveto be cut manually with a scissors by the operator, a cutting mechanismhas already been developed by which the cutting knife is disengaged fromits oscillating drive and allowed to be swung by means of a hand lever,so that the knife blade is drawn forward against the feed direction ofthe sewed material to thereby cut-off or separate the excess strip ofmaterial (which has already been partially cut parallel to thestitching) in a so-called discharge cut. This application of the cuttingknife requires moving of the hand lever and the expenditure ofcomparatively large energy. This energy is greater, the thicker and moreresistant is the lining material.

In order to reduce energy required to accomplish the discharge cutting,this invention provides for imparting the oscillating movements to thecutter blade during the discharge cutting to assist said cutting. Theobjects of the invention are attained by supporting an oscillating leveron a fulcrum axle which, in turn, is supported by a bracket fordisplacement of the fulcrumed axle to thereby vary the range throughwhich the cutting blade oscillates the bracket, at least adjacent thefulcrumed axle, being movable in a plane which is parallel to the planeof the oscillating lever and is substantially vertical to a straightline, which passes through the point connecting the oscillating leverwith the driving means and the point from which it is driven.

Through the resulting displacement of the oscillating range of the knifeblade toward the feed direction of the to-be-sewed material in front ofthe stitch structure site, the edge band of the lining will accordinglybe cut off during the discharge cutting, in the same way as during themain cutting process. The work discharge by discharge cutting isdistinguished from the main cutting essentially only in that therelative movement between the lining material and the oscillating drivenknife edge is accomplished in the first case through the feedingmovement of the cutting blade, and in the second case through thefeeding movement of the sewed material. The manually operated feedmovement of the cutting action, which is overlapped by the mechanicallyproduced oscillating movements, accordingly will be put into effect bythe oerator only during a part of the cutting operation. Accordingly,the cutting apparatus of the invention requires the operator to expandless energy in the discharge cutting than the known cutting devices.

The inventive proposal is also applicable to cutting devices in whichthe cutting knife is not driven directly by the oscillating lever, butindirectly through an interposed auxillary member.

Further features and advantages of the invention will be apparent fromthe reading of the subjoined specification and from a consideration ofthe accompanying drawings.

IN THE DRAWINGS FIG. 1 is a side elevation of a support column of asewing machine containing the cutting device of the invention shown inits normal cutting position.

FIG. 2 is a partly cut away front view of the disconnecting mechanism ofthe cutting device.

FIG. 3 is a plan view of the goods-support column of the sewing machine,with unimportant parts omitted, the solid lines showing the position ofthe cutting knife in normal cutting position, and the dot-dash linesshowing the position at the end of the discharge cutting.

On the base plate 1 of the housing 2, the supporting column 3 isfastened. It carries the advancing rod VR for forwarding the sewed goodsin the direction N. At the side of column 3, a bearing plate 4 isarranged for the reception of the cutting mechanism.

In the bearing plate 4,.a vertical, oscillating axle 5 is arranged, onwhose upper end a supporting link 6 is clamped. On the supporting link6, a vertical side arm 7 of an angled cutter-carrier 8 is adjustablyarranged, the other side arm 9 extending at the upper part of thesurface of the supporting column 3. On the arm 9 is fastened theextendible cutting knife 11 which is essentially balanced with respectto the needle hole 10 and which is adjustable in the direction of thehole 10. On the free end of the cutting knife 11, a right angleddownwardly directed curved lip 12 is provided, whose radius of curvatureessentially corresponds to the distance between the lip 12 and theoscillating axis of oscillating axle 5. The lip 12 is sharpened on itsforward side to an edge 13, which is adjusted to slope downward in thecutting direction and is normally cutting close beside the hole 10. Thatbalancing part of the knife blade 11, in the range of the edge 13,satisfies, in this explanatory example, the function of an improvedsafety flange, which serves in addition to keep the edge 13 from cuttingthe upper material.

The cutting blade 1 l is driven from a separate motor, not shown, whichis positioned under base plate 1 imparts about 2,800 revolutions perminute to axle 14. The eccentric 15 is fastened on axle 14 and isencircled by eccentric rod 16. The other end! of rod 16 is adjustablyconnected the lower end 17 of rocking lever 18, which is joumaled foroscillation in bracket 19 through bolt or fulcrum axle 20. Theessentially plate-form bracket 19 is pivotally mounted in housing 2 bystationary bolt 21 and has a laterally projecting arm 22, provided witha hole 23, which serves for the connection of the bracket 17 to a foot,knee, or hand lever (not shown) by means of a connecting rod (notshown). A tension spring 24, having one end connected to housing 2 andone end connected to arm 22, holds thebracket 19 in its normal position,said bracket also being held by means of the stationary bolt 25 whichengages through the slotted opening 26 thereof.

On the upper end 27 of the two-arm oscillating lever 18, another lever28 is arranged, which is joined to the driving element 29 for the lowerend of the freely rotatable oscillating axle 5. The driving element 29carries on bolt 31, a rotatable pawl 32 which by means of compressionspring 33 is held in its upper position as shown in FIG. 2. Pawl 32, inits upper position, fits into slot 34 of dog 35, which is fixed to axle5, so that oscillation of pawl 32 oscillates axle 5. The pawl 32 can beremoved from slot 34 by pressing handle 40 downwardly against the actionof spring 39 and so as to press the tripping pin 42, against the actionof spring 43, to rotate pawl 32 in a clockwise direction.

Above the shift lever 37, a guide ring 44 is fastened on the axle 5 onwhich is provided a projecting fitted pin 45. On the shift lever 37 isfastened the vertical stop pin 46 to limit the swivel range of the pin45. Between the shift lever 37 and the guide ring 44, there is provided,on the axle 5, a torsion spring 47, one end of which is fastened in theshift lever and the other end in the guide ring 44.

The apparatus of the invention operates as follows:

The oscillation drive of eccentric is transmitted over rod 16, rockinglever 18, and guide rod 28 to the drive element 29. From there, thedrive movement continues over the pawl 32, the dog 35 to the oscillatingaxle 5, so that axle 5 oscillates around its longitudinal axis andoscillatingly drives the cutting knife 11. The oscillating swing ofcutting edge 13 is adjustable through a distance of between 2 and 3.5 mmby shifting of the pivot point of eccentric rod 16 in the slot providedin the lower end 17 of lever 18. The cutting knife 11 cuts during thesewing process close to the stitch forming part of the lining on shoestock, respectively, generally the lower of two superposed layers ofmaterial. The cutting thrust is thereby successfully executed with theseam formation on the advancing movement of the sewed material.

Frequently, the lining material extends beyond the edge of the uppermaterial and for this case, the seam will end at this edge of the uppermaterial with the lining cut only up to this edge. Thus the stitchedside of the seam of the cut lining-band is still connected to the sewedmaterial through the edge uncut portion of the lining material. For thecomplete cutting off of the lining band, while the sewing machine is atrest but while the knife 11 is still being oscillated as before, bracket19 is swung in a clock-wise direction about bolt 21 by means of a foot,knee, or hand lever (not shown), connected to hole 23, for example.Simultaneously therewith, the swing lever 18 is likewise swung in aclockwise direction around the pivot point on the eccentric rod 16 andas a result thereof, the swing axis 30 (FIG. 2) of sewing lever 18(determined by bolt and the guide rod 28 shifts correspondingly to theright with respect to FIG. 1.

The drive 29, arranged between rod 28 and the axle 5, has the functionof a crank arm. Thence the shifting of rod 28 leads to a rotation ofdrive 29 and the axle 5 and consequently to a swivelling with the swingaxle 5 of the connected cutting knife 11. As shown in FIG. 3, therotation of axle 5 results respectively, in the swivelling of cuttingknife 11 in the counter-clockwise direction with respect to the planview, whereby the edge 13 moves essentially counter to the feeddirection N of sewed goods. Concerning the safety, to be able to cutwide overlying lining strip, the long slotted hole 26 in bracket 19 isconstructed large enough so that the blade 13 is shiftable up to aboutl5 mm. ahead of the stitch tap hole 10. According to the invention, thecutting apparatus is driven independently of the sewing device, also thecutting knife 11 is oscillated during the swinging process so that theoscillating movement is superimposed on the swinging movement. Thus,when bracket 19 is swung in the clockwise direction, the knife 13 willalso be shifted essentially against the feed direction N of the sewinggoods and thereby will completely cut the hanging lining tape on the endof the sewing material in so-called discharge cut. The higher theoscillating frequency and the greater the swing breadth or distance is,so much the greater is the share of cutting energy that the oscillatingmovement contributes to the total energy required for the cuttingoperation.

As soon as the finished lining tape is cut off, the operator releasesthe foot, knee, or hand lever, whereupon the tension spring 24 ofsupport 19 draws the support back to the starting position after whichthe knife blade 11 and the oscillating drive therefor are in the normalposition.

To now remove the blade 11 from the normal working position and into arest position, the handle will be tilted downwardly against the actionof spring 39. Thereby it presses on the tripping pin 42, whereupon thisturns the pawl 32 in the clockwise direction. As soon as the projectingpart of pawl 32 is withdrawn from the slot 34 of the dog 35, the driveconnection on the oscillating axle 5 is interrupted. Simultaneously thetorsion spring 36 is able to rotate the swing axle 5 in a clockwisedirection until the pin strikes the stop pin 46. By this movement of theswing axle 5, the knife 13 is moved in the feed direction N of thesewing goods to a rest or inoperative position behind the normal workingposition and out to a rest position laterally behind the supportingcolumn 3.

For then engaging the cutting apparatus, the handle 40 is turnedbackwards against the force of the torsion spring 47. Thereby the stoppin 46 rotates the pin 45 and the guide ring 44 of swing axle 5 back tothe starting position so that the pawl 32 again engages the slit 34 ofthe dog 35 through force of the spring 33 and in this way the driveconnection between eccentric l5 and the oscillating axle 5 is againoperative. The support for the bolt carrying the oscillating lever on ahousing bracket of the sewing machine is provided with displacementmeans to shift the oscillating axle of the es cillating lever andthereby the oscillating range of the cutting knife. The supporttherefore being movable in a plane parallel to the plane of theoscillating lever and vertical to a straight line, which passes throughthe connecting point between the oscillating lever and the eccentric rodand the fastening place of the cutting knife on this oscillating lever.

We claim:

1. An apparatus for sewing machines for cutting the edges of sewed goodswith an oscillating cutting blade comprising a pivotally mountedvertical shaft for normally holding and oscillating said blade in theregion of the needle-hole,

drive means for oscillating said vertical shaft comprising eccentricmeans driven independently of the sewing means connected to one leg of alever with two legs fulcrumed on a shaft,

the excess side material from the sewed material. 2. An apparatus asclaimed in claim 1, comprising manual means to release the connectionbetween said oscillating lever and said vertical oscillating shaft,spring means on said vertical oscillating shaft which upon release ofsaid connection swings said shaft and the cutting blade in the feeddirection of the material to be sewed to a rest position away from theneedlehole.

1. An apparatus for sewing machines for cutting the edges of sewed goods with an oscillating cutting blade comprising a pivotally mounted vertical shaft for normally holding and oscillating said blade in the region of the needle-hole, drive means for oscillating said vertical shaft comprising eccentric means driven independently of the sewing means connected to one leg of a lever with two legs fulcrumed on a shaft, a pivotable bracket carrying said shaft for the lever with two legs, means releasably connecting the other leg of said lever to said pivotally mounted vertical shaft, spring means normally holding said pivotable bracket in such a position that the blade is oscillated in the region of the needle-hole, said bracket comprising means for manually pivoting the same so that the blade, while still oscillating, shifts in a direction toward the feed direction of the material being sewed, whereby to completely cut the excess side material from the sewed material.
 2. An apparatus as claimed in claim 1, comprising manual means to release the connection between said oscillating lever and said vertical oscillating shaft, spring means on said vertical oscillating shaft which upon release of said connection swings said shaft and the cutting blade in the feed direction of the material to be sewed to a rest position away from the needle-hole. 